Arduino in a Nutshell 1.8

8/13/2019 Arduino in a Nutshell 1.8

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Arduino

in a Nutshell

Jan Borchers

Version 1.8 (Aug 5, 2013)

for Arduino Uno R3 & Arduino IDE 1.0.5

Latest version at: hci.rwth-aachen.de/arduino
http://hci.rwth-aachen.de/borchershttp://hci.rwth-aachen.de/borchers


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I. INTRODUCTION

The Arduino is a family of

microcontroller boardsto simplify

electronic design, prototyping

and experimenting for artists,

hackers, hobbyists, but also many

professionals. Use it as brains for your robot, to build a

new digital music instrument, or to make your house plant

tweet you when its dry. Know a little programming, but

no electronics? This book will get you started quickly.

Arduinos (we use the standard Arduino Uno R3) contain

an ATmega microcontroller thats a complete computer

with CPU, RAM, Flash memory, and input/output pins,

all on a single chip. Unlike, say, a Raspberry Pi, its

designed to attach all kinds of sensors, LEDs, small

motors and speakers, servos, etc. directly to these pins,

which can read in or output digital or analog voltages

between 0 and 5 volts. The Arduino connects to your

computer via USB, where you program it in a simple

language (C/C++, similar to Java) inside the free

Arduino IDE by uploading your compiled code to the board.

Once programmed, the Arduino can run with the USB

link back to your computer, or stand-alone without it

no keyboard or screen needed, just power.

Arduino in a Nutshell 3


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II. GETTING STARTED: BLINK AN LED!1.Get the MAKE Ultimate Micro-

controller Packwith an Arduino Uno

R3from makershed.comor your local RadioShack

($149). Also get a standard USBA-B cable and a 9V

battery. Or, for just the parts well use here, get the

Wish Listat sparkfun.com/wish_lists/46366($63).

SparkFuns Inventors Kit or Adafruits Experimenta-tion Kitalso have most parts we need, and more.

2. Download and install the Arduino IDEfor Mac, Linux

or Windows from arduino.cc. Windows users also

need to install a driver .INF file, see the website.

3. Connect your board via USB. Launch the Arduino

app. From the Tools:Board menu, select Arduino Uno.

From the Tools: Serial Portmenu, select the new serial

port(/dev/tty.usbmodem... on Macs).Open the

sketch (program) File:Examples:01.Basics:Blink . Click

thetoolbar button toupload it to your board.

After some flickering, its tiny yellow LED should blink

regularly (1 second on, 1 second off). Youve

programmed your first microcontroller!Change the

durations in delay()and upload to see the effect.

4 Arduino in a Nutshell
http://arduino.cc/https://www.sparkfun.com/wish_lists/46366https://www.sparkfun.com/wish_lists/46366http://www.makershed.com/Ultimate_Microcontroller_Pack_p/msump.htmhttp://arduino.cc/http://arduino.cc/https://www.sparkfun.com/wish_lists/46366https://www.sparkfun.com/wish_lists/46366http://www.makershed.com/Ultimate_Microcontroller_Pack_p/msump.htmhttp://www.makershed.com/Ultimate_Microcontroller_Pack_p/msump.htm


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III. RUN WITHOUT A COMPUTER

1. Disconnectthe USB cable from your board.

2. Put the 9V batteryinto the battery case(takes some

fiddling).

3. Plug the barrel plugfrom the battery case into the

round socketon the Arduino, and turn on the switch

on the battery case if it has one.

4. Your sketch starts running as soon as the board is

powered up, and the LED blinks, until you turn off

power no computer needed!Thats a great way to

build small, autonomoussystems around an Arduino.

The Arduino convertsthe 9V from the battery down to 5Vusing a regulator on the board. You can also connect

anything from 712volts DC to the barrel plug socket

(2.1 mm / 5.5 mm diameter, center positive), or stick

cables directly into the Vinand GND (Ground) pins to

power the board from 712 volts great if you dont

have a barrel plug on your power source.

Dont attach a 5V power source directly to the +5V pin

though its a voltage outputpin only, and you may fry

your onboard regulator. Use the USB connector instead.



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IV. CONNECT A BIG LED

1.Always disconnect or turn

off your power source before

you change your circuit to

avoid shorts. They may shut

down your USB port, or

worse.

2. Bend and stick the longerlead (+) of any red, yellow

or green LEDinto Digital Pin 13 on the Arduino. Stick

its shorterlead () into the GND pin next to pin 13,

as shown.

3. Connect USB now your big LED blinkstoo.

The Blink sketch outputs ahigh signal (5V)on pin 13

using digitalWrite(led,HIGH); waits for 1000 ms (1 s)

using delay(1000);then outputs a low signal (0V) and

waits another second. This makes your LED blink. The

yellow onboard LED is also connected to pin 13, so it

blinks along.

Every Arduino sketch has one setup() method that runs

once whenever the Arduino powers up or resets, and a

loop() function that is repeatedafter that until the board

is powered off or reset again. No OS, no multiple apps!


Made with Fritzing.org


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V. ADD A RESISTOR

Connecting an LED directly to 5V and GND will usually

fryit because of too much current flowing through it. It

survived only because the Arduino cant provide more

than 40 mA(milliamps) of current on each pin.

Thats still more than the 20 mAstandard LEDs like and

need, however. LEDs also drop(consume) around 2Vof

forward voltage (Vf). For precise values, google, e.g.,

SparkFun red 5mm LED (SparkFunsells great basic

components and documents them well). To limit the

current, add a resistorbefore or after the LED.

Whats the right resistor value? The Arduino pins provide

5V. 2V are dropped by the LED. That leaves 3V to dropover the resistor, at a current of 20 mA. Ohms law (I use

the picture on the right to remember it) says

U (voltage) = R (resistance) x I (current), or

R = U / I = 3 V / 20 mA = 3 V / 0.02 A = 150 !.

Choose the next bigger resistoryou have; in our case its330 !(OrangeOrangeBrownGold). Use the color

code tablein the Make Pack booklet, google resistor

color codes, or get Adafruits simple Circuit Playground

app or the comprehensive Electronic Toolbox Proapp for

your iPhone/iPad.


UR I
http://adafruit.com/circuitplaygroundhttp://www.sparkfun.com/http://itunes.apple.com/us/app/electronic-toolbox-pro/id339158729?mt=8http://itunes.apple.com/us/app/electronic-toolbox-pro/id339158729?mt=8http://adafruit.com/circuitplaygroundhttp://adafruit.com/circuitplaygroundhttp://www.sparkfun.com/http://www.sparkfun.com/


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Disconnect USB. In themini

solderless breadboard, each

vertical columnof 5 holes is

connectedinside the board.Stick the LED, 330 "resistor

and jumper wires in as shown.

Current will now flow from

Arduino pin 13 through the

resistorand the LEDto GND

when pin 13 is HIGH.

Connect USB. Your LED will glow slightly less brightthan

before, but will last forever. The current is now around 3

V / 330 "= 9 mA. Current is the same everywhere in a

simple closed circuit without branches. So it doesnt

matter if you put the resistor before or after the LED.



Tip: Alwaysuse red wiresfor connections to 5V, black

wiresfor connections to GND, and other colors using a

schema you like. I use yellow wiresfor outputs to LEDs,

green wiresfor outputs to motors and servos, and bluewiresfor sensor inputs. Itll help avoid confusion, short-

circuits, and fried components. Trust me; Ive been there.


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VI. DIGITAL INPUT: READ A BUTTONDisconnect USB. Add a

pushbutton, 10 k!resistor

(BrownBlackOrange

Gold) and wiresas shown.

Orient the button so the pins

that are closerare nextto

each other. These connectwhen you push it; the pins

below each other are

always connected.

Change the Blinkcode so it only blinks the LED while pin

2 is LOW: Define a global integer (int) variablepushbutton. Set it to 2 in your setup(). In your loop()

code, use if (digitalRead(button)==LOW) {...}. Dont

forget the curly braces and the double equal sign. Now,

the LED will only blink while you press the pushbutton!

We are using pin 2as a digitalinputto detect if itsvoltage is closer to GND or 5V. Every digital pin 0..13

can be an input or output pin. While input is the default,

its good style to add pinMode(pushbutton,INPUT);to

your setup()function to make it more readable.

Remember to end each statement with a semicolon.




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The 10 k"resistor is a pullup resistor. It provides a

defined voltage (5V) to pin 2 when the button switch is

open (it pulls it up to 5V). Otherwise pin 2 would be

connected to nothing, or floating, and pick up random

electromagnetic noise like an antenna, leading to

unpredictable HIGH/LOW values when you read it.

When you push the button, it pulls pin 2 low (connects it

to GND = 0V), and a small current flows through the

resistor and switch to GND. All 5V then drop across

the resistor. Arduino inputs themselves just measure the

voltage on their pins while consuming hardly any current.

VII. INTERNAL PULLUP RESISTORS

Remove the 10 k"pullup resistor from the board. Now

your LED may be blinking or not, since pin 2 is floating.

Change setup()to say pinMode(button, INPUT_PULLUP);

and upload.This connects an internal pullup resistor to

that pin inside the ATmega chip. It works like your

external pullup resistor, but you can simplify your circuit.


Tip: Forhelpwith any function, click on it, then select the

Help:Find In Reference menu. I also use the language

reference at arduino.cc/en/Referencea lot; more

tutorials are at arduino.cc/en/Tutorial/Foundations.
http://arduino.cc/en/Tutorial/Foundationshttp://arduino.cc/en/Referencehttp://arduino.cc/en/Tutorial/Foundationshttp://arduino.cc/en/Tutorial/Foundationshttp://arduino.cc/en/Referencehttp://arduino.cc/en/Referencehttp://arduino.cc/en/Tutorial/Foundationshttp://arduino.cc/en/Tutorial/Foundationshttp://arduino.cc/en/Referencehttp://arduino.cc/en/Reference


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VIII. READING ANALOG VALUESDisconnect USB.Remove the

pushbutton and connect a

force-sensitive resistor,the

10k"resistor and wires to

analog input A0as shown.

Youve created a voltage

divider. Normally the force

sensor has a resistance much

higher than 10 k", so A0 gets

pulled to near 0V by the

10k"resistor. Press on the

force sensor, and you lower itsresistance. It can go way

below 10 k", and the voltage on A0 then goes up to

almost 5V. So: more pressure higher voltage. Thats

how you can read continuous (analog) values.

Load File:Examples:03. Analog:AnalogInput. It usesanalogRead(...)to read the voltage on A0, and turns the

LED on and off with a delay determined by that voltage

the harder you press, the slower the LED will blink.

analogRead() returns values from 0 (0V) to 1023(5V).


Made with Fritzing.or


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IX. DEBUGGING USING SERIAL OUTPUT

Its hard to really see what values youre getting from the

force sensor through the analog pin just by looking at the

blink frequency of that LED. To see the actual numbers,

open File:Examples:01.Basics:AnalogReadSerial. Upload

it, then click on the magnifiertoolbar button in the top

right to open the Serial Monitor

window. Youll see values

changing as you press the sensor.

The code uses Serial.begin(9600) to open a serial

connection back to your computer in setup(), and

Serial.println(...)to output (print) numbers to that serial

connection, which end up in the Serial Monitor window

on your screen. Its also possible to send data back to

the Arduino that way, using Serial.read(...).



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X. ANALOG OUTPUT AND PWMDisconnect USB.Move the

yellow wire from pin 13 to pin

11. Pin 11 has a tilde (~)on

the board, which means it can

output analog values.

Change your loop() to control

the LED with analogWrite(...).

Analog values for output go

from 0 to 255, not 1023, so

divide the value from

analogRead(...) by 4 before

writing it to the LED pin.

Connect USB and upload your code. Now

you can control the brightness of your LED

by pressing on the force sensor.

Arduino uses Pulse-Width Modulation (PWM)to create

analog values itll turn the output on (5V) and off (0V)

at 500 Hz, and increase the duty cycle (relative on-time)

of that square wave signal to represent higher analog

values. 500 Hz is too fast for the human eye, so the LED

looks like its always on, just more or less bright.


Made with Fritzing.or


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However, the Servo libraryfor Arduino takes care of all

this. Note the #importstatement, the Servoobject

declaration, and how the sample code then sends data to

the servo using angular values. You can easily declare,create, and control two or more Servo objects this way

essential for your robot!

Servos can take around 0.51s to reach their target

position. For a simple walking movement, you can just

send the maximum angle, wait, then send the minimumangle, wait, and so on.


Tip:If you run out of 5V pins on the Arduino, bring 5V

over to a columnon the breadboard, and connect things

from there (similar for GND). Use red and black wires to

keep your sanity! On larger breadboards like the large

one in the MAKE Pack, use the horizontal connector rows

(rails) along the top and bottom put 5V only to the

top red rail, and GND only to the bottom blue rail, to

avoid plugging things into the wrong one.


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XII. SHIELDS

Shields are PCBs that stack on top of the Arduinoand

connect to all Arduino pins to add all kinds of hardware

features. There are shields to play MP3 files, for WiFi,

Bluetooth, Ethernet, Zigbee, MIDI, GPS, to log data,

drive big motors, etc. shieldlist.orglists over 200!

Good shields are stackablethey have the same female

header pins as the Arduino on top.

The MAKE Pack contains a kit for a

MakerShieldprototyping shield

(see photo). Solderit together (URL

for instructions on the pack), stick

the mini breadboard onto it, and

you have a very useful board with

some built-in LEDs, buttons, even a

potentiometer for quick experiments. Its not a perfect fit

for the Arduino, but it works well enough. SparkFunhas a

similar ProtoShield.

RadioShack also carries a simpler, but more modern

prototyping shielddesigned by the Arduino team, to

solder your own parts onto. In the future, look for shields

like that one, with 18 pins at the top, which is the new

Arduino standard.

http://www.sparkfun.com/products/7914http://www.makershed.com/MakerShield_p/msms01.htmhttp://www.sparkfun.com/products/7914http://www.sparkfun.com/products/7914http://www.makershed.com/MakerShield_p/msms01.htmhttp://www.makershed.com/MakerShield_p/msms01.htmhttp://shieldlist.org/http://shieldlist.org/


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Digikey.com, Mouser.com,and Farnell.comare

professional electronic component vendors. They carry

and have datasheets for everything, at the best prices if

you know what youre looking for, but they areoverwhelmingto beginners try SparkFun, MakerShed,

Adafruit or RadioShack at first.

Fritzing.orghas a nice free tool to document your

Arduino breadboard designs, and to design shields that

can then be made by submitting your files to an onlinePCB maker. I used it for all the Arduino diagrams here.

In general, if you want to hook up X to an Arduino,

google Arduino Xand youre likely to find a solution. :)

Look for the above sites among the search results.

There are countless Arduino booksout there; the gentlest

is probably Massimo Banzis Getting Started With

Arduino (he designed the Arduino board). The PDF is ten

bucks at theMakershed. Tom Igoes Making Things Talk

is excellent and beautifully designed, focusing on making

Arduinos and other electronic devices connect and shareinformation. Arduino Bots and Gadgetsis interesting if

you want to build robots. However, all Arduino books

become outdated quicklybecause the Arduino boards

and IDE have changed slightly almost every year so far.

Look for a book edition thats no older than a year.

http://fritzing.org/http://fritzing.org/http://digikey.com/http://mouser.com/http://farnell.com/http://fritzing.org/http://fritzing.org/http://farnell.com/http://farnell.com/http://mouser.com/http://mouser.com/http://digikey.com/http://digikey.com/


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For a current book on basic electronics(not

Arduino), there is no better choice than Make:

Electronicsby Charles Platt. Beautifully illustrated,

starts with the basics, very accessible and fun.And experiment #1 is licking a 9V battery. I read

it cover to cover to refresh my electronics knowledge.

In general, OReilly.comhas excellent books on Arduino

and other techie topics, with DRM-free versions for iPads

and in PDF, lifetime access and dropbox syncing,frequent updatesof their PDF editions, 3-for-2 deals, and

special pricing if you own the printed book.

There are dozens of different Arduino boards out there.

Stick with those documented on arduino.cc at first. Their

new Leonardo board, e.g., can act as a USB keyboard ormouse, the new Due is faster, and SparkFuns Arduino

Pro Micro (right) is a great tiny option, but for a

beginner theyre not quite as smooth to use yet.

Without a doubt this version of

this guide will become outdatedjust as quickly as all those

books. Check back at the URL on

the front cover for updates, and

meanwhile, have fun hacking

and making with Arduino!

http://oreilly.com/http://oreilly.com/http://oreilly.com/


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About the author

Jan Borchersis a professor of computer science and head of the

Media Computing Group at RWTH Aachen University. He works in

human-computer interaction, usability, and digital fabrication, and has

taught Arduino to students and kids since 2008.

Feel free to use this booklet for yourself, with your

friends, or in noncommercial classes. Instead of

hosting a local copy, please link back to the URLon

the cover so we can keep old versions from floating around. Ill keep

older versions of the booklet there for reference. Thanks!

This work is licensed under the Creative Commons Attribution-

NonCommercial-NoDerivs3.0 Unported License. To view a copy of this

license, visit creativecommons.org/licenses/by-nc-nd/3.0/. For otheruses, including commercial or derivative works, contact the author.

Version history

2013-08-05 (1.8): Added QR code, adjusted cover page graphics.

2013-07-31 (1.7): Clarified p.4, updated SparkFun prices, corrected pinModetypo, updated for IDE 1.0.5.

2013-01-24 (1.6): Added target audience, author info, premium headers on

wishlist. Updated pushbutton declaration. Updated for IDE 1.0.2 & 1.0.3.Cosmetic corrections throughout.

2012-08-17 (1.5): Corrected button use in Ch.VI. Changed title page, tipslayout, last page layout.

2012-08-15 (1.4): Added shieldlist.org.

2012-08-15 (1.3): Updated acknowledgements, Java reference, +5V pin,

enabling pullups, page footers, layout. Added Creative Commons license

terms.

2012-08-15 (1.2): Added: cropmarks, boldface in first chapters, Raspberry Pi,SparkFun wish list, other starter kits, Electronic Toolbox, Arduino Pro

Micro, Make: Electronics cover, double-sided layout for binding. Edited:

shields, OReilly, title, headings.

2012-08-12 (1.1): Added: missing sensor wire in ch. X+XI diagrams, Circuit

Playground, different boards, version history. Fixed typos.

2012-08-09 (1.0): Initial release, see Acknowledgements.
http://creativecommons.org/licenses/by-nc-nd/3.0/http://creativecommons.org/licenses/by-nc-nd/3.0/http://creativecommons.org/licenses/by-nc-nd/3.0/http://creativecommons.org/licenses/by-nc-nd/3.0/

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